▎ 摘　　要

In this theoretical study, we perform direct ab initio molecular dynamic simulations for the collisions of Cr/Fe atom/dimer with the graphene surface to study the evolution of magnetic moment. During the dynamic process, the change in magnetic behavior of those systems is monitored and explained in accordance with the spin-polarized electronic structure analysis. While the magnetic moment of Fe dimer is found to remain almost unchanged (total magnetization > 6 mu(B)) on the graphene surface, we find that the Cr dimer-graphene system possesses either 0 (non-magnetic) or a ferromagnetic state of similar to 10 mu(B). Those observations offer explanations to the switch of magnetic states during the collision dynamics. (C) 2016 Elsevier Ltd. All rights reserved.